Pros: Sound quality, build quality, easy to use and overall great performer
Cons: Lacks some detail, only USB digital input
I've had it close to a year now, and this unit has become my favorite piece of stereo equipment. After purchasing the GT40, the 2,000$ Hegel HD20 DAC/preamp came and went, so did the 900$ Burson HA-160DS DAC/headphone amplifier. I got the GT40 last fall, at the time I bought it primarily as a phono stage/preamp since I just got my first turntable. I've always loved swiss knives, and the What HiFi award and multiple other awards conviced me to buy it. At first I didn't realize how awesome this unit was.
As a headphone amp/DAC: The Furutech ADL GT40 and Beyerdynamic T1 are a beautiful couple. My T1 dated the Burson HA-160DS for a few months, but their relationship was boring. I could plug IEMs to the Burson and turn the volume way up and not hear any noise, it was silent as the grave. I could not say the same for the GT40, but the noise is not audible during normal use. Burson might have had a more balanced and detailed presentation, but not so much that I actually could hear any difference in a side by side comparison. I would never reach for my cans unless I thought to myself that I had to use this expensive equipment I bought, but I tired quickly and would never listen to a whole record. So I went back to GT40, it might not be pretty, but is a bunch of fun! I can sit for a whole day now without taking my headphones off. The sound is warm, engaging and musical. I love everything about it.
As a DAC/preamp: My Hegel DAC/preamp had more detailed sound than the GT40, it was easy to hear in a side by side comparison. But again, I felt the sound was boring and didn't move me. So I sold it earlier this week, and for the money I sold it for I am thinking of buying the Furutech ADL Espirit.
As a phonostage: Well, I don't have anything to compare to. I use it with a Technics SL-1200 turntable, Denon and Ortofon cartridges. All I can say is that I'm very happy with the sound, and I can clearly hear the difference in sound between digital and analog sources in my system.
The build quality seems good, it's plug and play, very easy to operate and the sound is a perfect match for me and my system. I would have liked it to have as many connections as the prototype (which is why I'm considering the Espirit) and some more detail, but other than that I can do nothing but praise this little wonder.